A federal inquiry into an oil spill off the northern coast of Western Australia last year will begin in Canberra today.

Oil and gas from the Montara well began leaking into the Timor Sea last August, causing thousands of barrels of oil and gas to spill into the ocean off the Kimberley coast.

The leak, which continued for more than 10 weeks, was eventually stopped when heavy mud was pumped down a relief well.

The inquiry will examine what caused the leak, how it was managed and its environmental impact.

Many submissions to the inquiry call for tougher regulation of the oil and gas industry, with stronger protection for the marine environment in oceans to the north and west of the country.

Submissions have also complained about a lack of transparency during the incident.

WA Greens Senator Rachel Siewert says she will be closely monitoring the inquiry as the Greens want answers.

“There’s a range of issues around the regulations, the response time, the response process, how decisions were made, who made the decisions, the fact that the company wasn’t sharing information, what caused the accident,” she said.

“Obviously, we want to see a thorough analysis of cause of the accident, the technicalities involved but also the environmental impacts and the reasons what were the successes and what were the failures.”

Witnesses from the well’s owner, Thai-based company PTTEP Australasia, will give evidence during the inquiry which will be led by former public servant David Borthwick.

A report on the accident will be submitted by the end of April.